Pneumatic motor mechanism for hand tools



Jan. 3, 1967 w. J. BROWN 3,295,262

PNEUMATIC MOTOR MECHANISM FOR HAND TOOLS Filed June 17, 1964 2 Sheets-Sheet 1 116 /04 48 100 46 44 9632 INVENTOR:

WILLIAM J- 820mm H15 HTTORA/E v Jan. 3, 1967 w. J. BROWN PNEUMATIC MOTOR MECHANISM FOR HAND TOOLS 2 Sheets-Sheet .2

Filed June 17, 1964 lA/VEN TO 123 WILL/HM J. BROWN,

H/ 5 QTTQENE Y United States Patent G 3,295,262 PNEUMATIC MOTOR MECHANISM FOR HAND TOOLS William J. Brown, St. Ann, Mo., assignor to General Pneumatic Products Corporation, St. Louis, Mo., a

corporation of Missouri Filed June 17, 1964, Ser. No. 375,739 6 Claims. (Cl. 51-170) The present invention relates generally to new and useful improvements in the construction of pneumatically operable hand tools, such as sanders, drills, grinders and the like. As a general rule, tools of this type have a con figuration resembling a pistol, in that they include a handle portion surmounted by a motor housing substantially normal thereto.

The rotary speed of such a tool is controlled by finger manipulations of a valve assembly mounted in the handle portion. conventionally in this art, such a control assembly is termed a trigger valve, and that term may sometimes be employed hereinafter.

The present invention is directed primarily to means in the motor housing for conserving air pressure. As is well known, during operations wherein conventional hand tools of the type under consideration are employed, much of the air pressure delivered to the tools is wasted to atmosphere. In accordance with the concepts of the present invention, these compressed air losses would be obviated. To this end, the invention teaches the provision of what will be termed an annular seal groove, and a pair of therewith associated passageway arrangements that are formed in the bore of the housing wherein the motor mechanism is supported.

The aforesaid annular seal groove is formed in the motor housing between the pressure intake and exhaust chambers, and includes a semicircular formation that merges into sloping side walls. The pair of passageway arrangements are diametrically opposite, and each arrangement includes a single passageway leading from the intake chamber, and two divergent passageways that lead from said single passageway to the seal groove.

The present invention furthermore teaches the seating in the semicircular formation of the aforesaid groove, of an annulus or ring of soft but resilient material. This ring is round in cross-section, the outer diameter thereof corresponds to that of the semicircular formation of the groove, and the inner diameter thereof corresponds to that of the bore in the motor supporting housing.

When the motor is in operation, back pressure built up in the housing rearwardly of the seal groove will be brought to bear against said ring via the passageway arrangements. Consequently as will be described in more detail hereinafter, the ring will be deformed into sealing engagement with one of the aforesaid sloping side walls of the seal groove, and the adjacent peripheral surface of the cage or rotor housing of the motor.

The provision of the seal groove, and the therewith associated pair of passageway arrangements in the bore of the motor housing, furthermore serves to cool the rotor housing, inasmuch as the compressed air built up therein will absorb the heat engendered by the repeated engagements of the rotor vanes or blades with the internal peripheral surface of said housing.

Accordingly, it is an object of the present invention to provide an annular seal groove of the contour described, in the bore of a pnuematic hand tool motor housing between the air intake and exhaust chambers formed therein.

It is another object to provide in said bore diametrically opposite pairs of passageway arrangements each establishing fluid communication between the air intake chamber and the aforesaid annular seal groove.

A further object of the invention is to provide an annulus or ring of the character described seated in the annular groove aforesaid.

A more comprehensive understanding of the advantages and features of the invention, the construction thereof, and its mode of operation, may be had from the detailed description that follows with reference to two sheets of drawings that accompany this specification. In these drawings, the invention is illustrated as embodied in a pneumatic speed sander, although as indicated hereinabove, it is not limited to sanders, but may be embodied in other hand tools that are similarly operable.

In said drawings:

FIGURE 1 is a top plan view of a sander embodying the pneumatic motor concept of the present invention;

FIGURE 2 is a side elevational view of the FIGURE 1 sander;

FIGURE 3 is a front elevational view of said sander on a reduced scale;

FIGURE 4 is a vertical sectional view on an enlarged scale, taken along the line 4-4 of FIGURE 1 with the elements included in the motor mechanism and the sealing ring being shown in elevation;

FIGURE 5 is a view similar to FIGURE 4 with some elements included in the motor mechanism as well as the sealing ring being shown in section;

FIGURE 6 is an enlarged horizontal sectional view taken on the line fi-d of FIGURE 2;

FIGURE 7 is a central vertical sectional view of the motor housing and a fragmentary portion of the handle that is integral therewith, this view being similar to FIG- URE 4 with the pneumatic motor mechanism and the air pressure control assembly illustrated in said FIGURE 4 removed;

FIGURE 8 is a view similar to FIGURE 7 that is taken on a plane directly opposite to that indicated by the line 4-4 of FIGURE 1;

FIGURE 9 is a vertical sectional view taken on the line 99 of FIGURE 5;

FIGURE 10 is a left end elevational view of the cage element or rotor housing component of the motor mechanism;

FIGURE 11 is a right end elevational view of the FIG- URE 1O component;

FIGURE 12 is a top plan thereof;

FIGURE 13 is a view of the annulus or seal ring of the invention per se;

FIGURE 14 is a schematic view, partly in section and on an enlarged scale, of a fragmentary portion of the motor housing, illustrating the normal status of the sealing ring of the present invention; and

FIGURE 15 is a similar view illustrating the status of .said sealing ring when the pneumatic motor is in operation.

The sander that incorporates the present invention is shown in its entirety in FIGURES 1 through 3, and is designated generally by the numeral 20. The illustrated sander includes a handle member generally designated 22; a manually operable air pressure control device or trigger valve generally designated 24; a pneumatic rotary motor mechanism generally designated 26; a sanding disk assembly generally designated 28; and other elements and associated parts to be described in detail hereinafter.

The handle member 22 is comprised of a hand grip section 30 surmounted by a motor housing 32 that is formed integrally therewith. As viewed in the drawings, the left hand or forward end of the housing 32 is open, whereas the right hand or rear end thereof is closed by an integral vertical wall 34. Formed centrally in the inner face of the wall 34, is a circular recess 36 that 3 'opens leftwardly into an annular groove 38 formed in the bore 40 of the housing 32, as best seen in FIGURES 7 and 8. As also seen to best advantage in these figures, -'and progressing from right to left, the surface of the bore 40 has also formed therein longitudinally spaced annular grooves 42, 44, 46, and threads 48.

The groove 42 is in communication with an air pressure delivery passageway 58 formed partly in the housing 32 and partly in the hand grip section 30 as shown. The groove 42 constitutes an air pressure intake chamber. The configuration of the annular seal groove 44 and the therewith associated air pressure passageways 52, 54, 56 are of prime importance in the attainment of the objectives of this invention. The pairs of grooves 52, 54, 56 are also formed in the bore 40 of the housing, and are diametrically oppositely disposed, as will be evident from a comparison of FIGURES 7 and 8.

With attention directed particularly to FIGURES 14 and 15, the groove 44 includes a semicircular formation designated 58 that merges at one side into what will be termed a forwardly sloping wall formation 60, and at the other side into what will be termed a rearwardly sloping wall formation 62. The passageways 52 are horitzontally disposed to communicate with the intake chamber formed by the annular groove 42, and lead forwardly therefrom and into the passageways 54 and 56, these last named passageways being divergent with respect to the passageways 52 as shown.

The groove 46 provides an annular exhaust chamber, and is in communication with an arcuate exhaust port 64. The threads 48 are provided adjacent the aforesaid open end of the housing 32 for a reason to appear.

It is observed at this point, that the present invention makes no claim to the hand grip section 30, nor to any of the therein incorporated structure. The control valve assembly 24 regulates the delivery of air under pressure from the intake passageway 66 to the delivery passageway 50 in conventional fashion. The assembly 24 is usually termed the trigger valve, and its operation is well understood. The lower end portion of the passageway 66 is threaded for the reception of a suitable fitting such as that suggested by broken lines in FIGURE 4, and designated 68. This fitting of course constitutes the discharge end of a flexible line 70, so that air under pressure from a source (not shown), would be continuously supplied to the passageway 66 via said line and fitting, as is understood.

The construction of the motor assembly 26, seen to best advantage in FIGURES and 6, is typical, and it will be understood that the details thereof may be modified without affecting the merits of the present invention. The motor assembly includes a rotor having a circular main body 72 provided with a series of radial slots 74. An impeller blade or vane 76 is slidably disposed in each slot 74 for radial movements therein responsive to centrifugal action in the well known manner. Projecting rearwardly from the main body thereof and integral therewith, the rotor is provided with a journal 78 of reduced diameter that terminates in a further reducedin-diameter extension 80 that projects into the recess 36 as shown. The journal 78 is rotatably supported in a suitable bearing assembly, a ball bearing assembly 82 being shown in the drawings.

Projecting forwardly from the rotor main body 72 and integral therewith is a journal 84 of reduced diameter. The journal 84 is also rotatably supported in a suitable bearing assembly, a ball bearing assembly 86 being shown in the drawings. Numeral 88 designates a drive shaft extension integral with the journal 84, and thus with the rotor. The drive shaft extension 88 is threaded so that it may be integrated with the sander disk assembly 28 as will appear.

The main body 72 of the rotor and the therewith associated vanes 76 revolve within a cage or rotor housing 90 that is illustrated per se in FIGURES 10, 11 and 12.

As there shown, the outer periphery of the housing is circular, whereas the inner peripheral surface thereof is eccentrically formed. The forward end face 92 of the housing 90 has formed therein a diagonal air exhaust recess 94 that communicates with the annular groove 46. The rearward end face 95 of the housing has formed therein an angular air pressure delivery recess 96 that, as particularly shown in FIGURES 5 and 9, is in communication with the annular groove 42, and thus with the air pressure passageway 50.

Preferably as shown, what will be termed a back end plate designated 98, is interposed about the rotor journal 78 between the rear end face of the housing 98 and the bearing assembly 82, this end plate serving to obviate rearward fiow of air pressure delivered via the recess 96 into the rotor housing chamber 97.

Similarly, what will be termed a front end plate designated 188, is interposed about the rotor journal 84 between the forward end face of the housing 90 and the bearing 86, this end plate serving to obviate forward flow of air pressure beyond the exhaust groove 46. The thus far described motor assembly 26 may have its included elements properly aligned prior to the insertion thereof into the housing 32, a pair of opposed fiat formations 182 being provided on the rotor extension 80 to facilitate such alignment, as should be apparent.

The properly aligned and disposed elements of the motor assembly 26 are maintained in position within the internal periphery of the housing 32 by means of a retainer 184. This retainer is in the form of a hollow cylindrical nut including an externally threaded portion 106 that engages the threads 48 aforesaid, and a forwardly projecting extension 108 that may have a pair of diametrically opposite fiat formations 110 thereon, whereby to facilitate rotation of said nut by means of a suitable tool, as should be understood.

With attention directed at this point particularly to FIGURES 5 and 9, it will be observed that when the motor elements are properly assembled and mounted in the housing 32, the air pressure from the passageway 50 would enter the annular groove 42, and would simultaneously be directed into the chamber 97 of the rotor housing via the angular recess 96. The end plate 98 lies flush against the rearward face 95 of the rotor housing 90, whereby to define with said recess an intake opening or orifice area that is constricted relatively to the discharge openings in the trigger valve 24 which transfer the air pressure from the passageway 66 into the passageway 56.

The assembly 28 includes: a sanding disc 112; a first back-up pad or disc 114 of smaller diameter; a second back-up pad or disc 116 of still smaller diameter; a mounting hub 118; and a circular pad nut 120. It is believed that the mounting arrangement of the assembly 28 on the drive shaft 88 should be apparent from an inspection of FIGURES 5 and 6. The discs 112, 114 and 116 have circular central openings whereinto is pressfitted the internally threaded hub portion of the nut 120, and are clamped between the outer face of the hub 118 and the annular end flange 122 of the pad nut. The mounting hub 118 is also internally threaded, and the entire assembly 28 may be securely threaded in place on the drive shaft 88 as shown, the hub 118 being provided with a socket 124 for the insertion of a suitable hub wrench (not shown).

Appearing per se in FIGURE 13 is a seal element in the form of an annulus or ring designated 130. The sealing ring 130, the annular groove 44, and the herein before described passageways 52, 54 and 56 cooperate in the attainment of the primary objectives of the present invention. The sealing ring is comprised of relatively soft but resilient material, such as rubber or neoprene.

As illustrated on an enlarged scale in FIGURE 14, the ring 130 is normally round in cross-section and has an outer peripheral diameter that corresponds with that of the semicircular formation 58 of the annular seal groove 44. The inner peripheral diameter of the ring corresponds with that of the bore 40, so that as should be apparent from an inspection of FIGURES 5 and 6, the motor assembly 26 may be inserted into and withdrawn from the housing 32, once the ring 130 has been seated in the groove 44, without difiiculty and without disturbing the seated status of said ring.

Prior to entering into an explanation of the advantages provided by the sealing ring 130 in cooperation with the groove arrangements 52, 54, 56 of the present invention, a few general observations will be given. Thus, the manual control assembly or trigger valve 24 illustrated in the drawings is typical only, and could well be replaced for example by the similar manually operable air pressure control assembly illustrated and described in detail in Letters Patent No. 2,655,901 issued on October 20, 1963 to Lowell N. Brown. In the drawings, the assembly 24 is shown in the inoperative or closed position thereof. As is well understood, when a mechanic depresses the finger piece a the air pressure being constantly delivered via the passageway 66 flows into the passageway 50, thence into the annular groove 42 and simultaneously via the port 96 into the rotor chamber 97. Thus, as viewed in FIGURE 9, the rotor 72 would rotate in a counterclockwise direction, and the air pressure after exerting its power against successive vanes 76, would exhaust to atmosphere via the recess 94, the annular groove 46, and the arcuate exhaust port 64. With respect to the assembly 28, centrifugal force maintains the sanding disk 112 in flat condition, so that it may be driven at speeds up to 16,000 revolutions per minute. The back-up pad discs 114 and 116 are made of fiber or similar material. The flange 122 of the pad nut 120 is thin, so that in actual operation, just about the entire abrasive area of the disc 112 may be applied to a work piece.

When compressed air is caused to flow from the intake passageway into the delivery passageway 50 in consequence of depressing the finger piece a of the trigger valve, back pressure builds up in the passageway 50 and the chamber formed by the annular groove 42, because the said valve will usually supply a greater volume of compressed air than can be utilized. Prior to the concept of the present invention, all such excess air pressure has been wasted. In other words, it would escape to atmosphere in conventional air motor constructions.

In the present construction, such back pressure is directed via the two passageways 52 into the two pairs of divergent passageways 5456 and against the resilient sealing ring 130. Inasmuch as said divergent passageways lead into the annular space defined by the rearwardly sloping wall formation 62, the pressure would be applied simultaneously to every thereto exposed area of the sealing ring 1130. Consequently, as visibly demonstrated in FIGURE 15, this pressure causes the ring to engage tightly against the forward sloping wall formation 60 of the groove 44. Furthermore the cross-sectional area of said ring becomes deformed under the pressure applied, so that it becomes impacted against the outer periphery of the rotor housing 90.

When the motor is put under load, the rotational speed of the rotor 72 diminishes somewhat, inasmuch as more pressure must be exerted against the vanes 76 in order to create the necessary torque for driving the rotor. Consequently at such times, slight additional back pressure will be built up to bear against the ring 130, thus enhancing the sealing eifect thereof. In other words, the greater the load, the tighter the seal.

From the foregoing description augmented by an inspection of the drawings, it should be apparent that the present invention provides novel means for achieving its objectives. Although particularly effective when incorporated in sanders, it should be understood that the invention is not limited thereto. In other words as here inbefore indicated, the present invention also contem- 6 plates its incorporation in pneumatic motor mechanisms for other hand tools in the instant category. Wherefore, although a preferred embodiment of this invention has been illustrated and described herein, the concept thereof is limited only by the scope of the claims hereunto appended.

What I claim is:

1. In a hand tool of the type described, said tool including a handle member surmounted by a housing normal thereto for supporting a pneumatically operable motor mechanism within the bore thereof, in combina tion:

an annular seal groove formed in the periphery of said bore between the air pressure intake chamber and the exhaust chamber provided in said bore;

a pair of diametrically opposed passageway arrangements formed in said bore between the annular seal groove aforesaid and said air pressure intake chamber, each of said passageway arrangements leading from said intake chamber to the seal groove;

and an annulus or sealing ring comprised of resilient material seated in said annular seal groove and surrounding the adjacent peripheral surface of the motor mechanism.

2. In a hand tool of the type described, said tool including a handle member surmounted by a housing normal thereto for supporting a pneumatically operable motor mechanism within the bore thereof, in combination:

an annular seal groove formed in the periphery of said bore between the air pressure intake chamber and the exhaust chamber provided in said bore, the contour of said seal groove being defined by a semicircular formation that merges into oppositely sloping side Wall formations;

a pair of diametrically opposed passageway arrangements formed in said bore between the annular seal groove aforesaid and said air pressure intake chamber, each of said arrangements including a horizontal passageway leading from said intake chamber and a pair of divergent passageways leading from the horizontal passageway to the annular seal groove;

and an annulus or sealing ring comprised of resilient material seated in said seal groove and surrounding the adjacent peripheral surface of the motor mechanism.

3. In a hand tool of the type described, said tool including a handle member surmounted by a housing normal thereto for supporting a pneumatically operable motor mechanism within the bore thereof, in combination:

an annular seal groove formed in the periphery of said bore between the air pressure intake chamber and the exhaust chamber provided in said bore, the con tour of said seal groove being defined by a semicircular formation that merges into oppositely sloping side wall formations;

a pair of diametrically opposed passageway arrangements formed in said bore between the annular seal groove aforesaid and said air pressure intake chamber, each of said arrangements including a horizontal passageway leading from said intake chamber and a pair of divergent grooves leading from the horizontal groove to the annular seal groove;

and an annulus or sealing ring comprised of soft resilient material seated in said seal groove and surrounding the adjacent peripheral surface of the motor mechanism, said annulus being round in cross section and having an outer periphery diametered in correspondence with the diameter of the semicircular formation aforesaid of the seal groove.

3,295,262 7 8 4. In pneumatic motor mechanism for hand tools of shaft for rotation therewith, said assembly including the type described, in combination: a sanding disc proper and a pair of smaller diama motor housing having a horizontal bore open at one etered back-up discs, all of said discs being mounted end and closed at its opposite end; on an internally threaded hub member in engagement a rotary motor structure mounted in the housing; with the threaded drive shaft aforesaid; spaced annular air intake and exhaust grooves formed spaced annular air intake and exhaust grooves formed in the bore of the housing; in the bore of the housing; an annular seal groove formed in the bore of the an annular seal groove formed in the bore of the houshousing intermediate said intake and exhaust ing intermediate said intake and exhaust grooves, grooves; 10 said seal groove comprising a semicircular formaa pair of diametrically opposite passageway arrangements formed in the bore of the housing between said intake groove and the seal groove, each arrangement including a horizontal passageway leading from said intake groove and merging into two divergent passageways leading to the seal groove, for establishing fluid communication between said grooves;

and an annulus of relatively soft resilient material seated in the seal groove, said annulus being round in cross section, and having an outer peripheral diameter that corresponds with the diameter of the seal groove, and an inner peripheral diameter that corresponds with the diameter of the housing bore.

5. In pneumatic motor mechanism for hand tools of the type described, in combination:

the structure recited in claim 4, wherein the annular seal groove includes a semicircular formation that merges into a pair of side wall formations that are divergent relatively to one another.

tion that merges at one side into a forwardly sloping wall formation and the other side into a rearwardly sloping wall formation;

a pair of diametrically opposite passageway arrangements formed in the bore of the housing between said intake groove and the sealing groove, each arrangement including a horizontal passageway leading from said intake groove and merging into two divergent sections leading to the seal groove for establishing fluid communication between said grooves;

and an annulus of relatively soft resilient material seated in said seal groove, said annulus being round in cross section, and having an outer peripheral diameter that corresponds with the diameter of the seal groove, and an inner peripheral diameter that corresponds with the diameter of the housing bore.

References Cited by the Examiner UNITED STATES PATENTS 6. In pneumatic motor mechanism for hand tools of 2,326,396 8/1943 Schaedler 9176 the type descnbed combmatm 2 888 679 6/1959 Peterssen 173169 X a motor housing having a horizontal bore open at one 3043274 7/1962 Quackenbu'sil 173 163 end and closed at its opposite end; 3111792 11/1963 Legg 51 177 a rotary motor structure mounted in the housing including an externally threaded drive shaft that projects through the open end of the housing;

a sanding disc assembly rigidly secured to said drive LESTER M. SWINGLE, Primary Examiner.

D. G. KELLY, Assistant Examiner. 

6. IN PNEUMATIC MOTOR MECHANISM FOR HAND TOOLS OF THE TYPE DESCRIBED, IN COMBINATION: A MOTOR HOUSING HAVING A HORIZONTAL BORE OPEN AT ONE END AND CLOSED AT ITS OPPOSITE END; A ROTARY MOTOR STRUCTURE MOUNTED IN THE HOUSING INCLUDING AN EXTERNALLY THREADED DRIVE SHAFT THAT PROJECTS THROUGH THE OPEN END OF THE HOUSING; A SANDING DISC ASSEMBLY RIGIDLY SECURED TO SAID DRIVE SHAFT FOR ROTATION THEREWITH, SAID ASSEMBLY INCLUDING A SANDING DISC PROPER AND A PAIR OF SMALLER DIAMETERED BACK-UP DISCS, ALL OF SAID DISCS BEING MOUNTED ON AN INTERNALLY THREADED HUB MEMBER IN ENGAGEMENT WITH THE THREADED DRIVE SHAFT AFORESAID; SPACED ANNULAR AIR INTAKE AND EXHAUST GROOVES FORMED IN THE BORE OF THE HOUSING; AN ANNULAR SEAL GROOVE FORMED IN THE BORE OF THE HOUSING INTERMEDIATE SAID INTAKE AND EXHAUST GROOVES, SAID SEAL GROOVE COMPRISING A SEMICIRCULAR FORMATION THAT MERGES AT ONE SIDE INTO A FORWARDLY SLOP- 